I started my mash around 7:00 p.m., was a little light on my target temp at around 150F. Was around 130F (or so) 9:00 a.m. the next morning. Wort smelled fine, the spent grains smelled a bit sour so we'll see.

I've done this twice (RIS and IPA) and the results were very good. No sourness noted, however my RIS was a little thin in body but that may be due to my initial mash temp, 154. I overnight mash in a Coleman Xtreme cooler. For my next brew I'm planning on mashing in at around 158 to hopefully get a little more body.

Hackwood, give it a shot! I'm beginning to love this method. It really opens up more brew days for me, since i can split it up and it's very difficult for me to be able to nail down 8+ hrs to brew. Overnight mashing is great for anyone who finds themself in a restricted schedule. Great beer can still be crafted despite the traditional methods. So much is said about LETTING the beer work for you, but not too often can we HELP the beer work with us.

On a side note, after several batches, I have yet to brew a sour batch.